


Under The Full Moon

by Indelible_Faith (TheWaterGoddess)



Category: Magic Kaito, 名探偵コナン | Detective Conan | Case Closed
Genre: And a murder almost takes place ....because of bad communication, Demons, Gen, Ghosts, Halloween Gift Exchange, I wrote this at 2 am pls ignore and plot holes thanks, Kaito is so done with everything and just wants to go home, Kudo and Hattori make a badaas ghost exorcisising duo, Magic
Language: English
Status: Completed
Published: 2020-11-28
Updated: 2020-11-28
Packaged: 2021-03-09 18:35:47
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,154
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27760870
Author URL: https://archiveofourown.org/users/TheWaterGoddess/pseuds/Indelible_Faith
Summary: In which, Kaito just wants to hold a heist in peace without getting pulled into a murder case; Akako has finally learned to use cellphones and give genuine advice; Kazuha would like to throttle Heiji for not relying on her protection charms; and Shinichi and Heiji want a full night’s sleep.
Relationships: Hattori Heiji & Kudou Shinichi | Edogawa Conan, Kudou Shinichi | Edogawa Conan & Kuroba Kaito | Kaitou Kid
Comments: 6
Kudos: 36
Collections: DCMK Fanfiction Server 2020 Halloween Exchange





	Under The Full Moon

**Author's Note:**

  * For [sylph_feather](https://archiveofourown.org/users/sylph_feather/gifts).



> For her prompt: ghost/demon au with some character AS the ghost/demon.
> 
> This story was written in the span of like, 5 hours, completed at 2 am because this is my life now. I'd be very obliged if you could pick out any typos and mention it to me

Hattori Heiji wasn’t called one of the best kendo practitioner’s in his age group for nothing. His skill was evident in the clean swing of his blade as he leapt down from the wall, slicing straight through the spirit haunting Tanaka-san’s backyard.

“Ugh,” said Conan at the wailing it produced as it disintegrated, “I hate these cases.”

“Sucks ta be you,” Hattori said with a grin, “you can go back to your usual techniques when you’re not two feet tall.”

“Three feet!”

“Eh, same difference.”

“No, that’s a whole thirty centimetres – twelve inches –”

“Okay, okay,” Hattori ruffled his hair, which Conan dodged, grumbling, and continued to smudge out the array they’d drawn to lure and trap the spirit in.

“Let’s go back,” he said finally, “Occhan’s protective talismans have a fifty-fifty chance of working, and I’d like to make sure we don’t have any more stragglers in this mansion before we leave.”

Hattori agreed, sheathing his katana as they walked back into the house, tired and eager to end the day with a good night’s rest. Unfortunately, the night was only getting started.

* * *

It began three days ago, with a heist note. And also, a visit from Tanaka Kazuto.

“There are very few Spirit Detectives,” Tanaka-san began, nervously wiping his forehead with a handkerchief, “and even fewer ones who are talented, but word goes around.”

Word certainly went around in  _ those _ circles. Hattori had arrived only hours before Tanaka-san had, called by Conan to discuss a slightly more important matter than a  _ haunting _ – but Tanaka had brightened upon seeing him. 

“There are the Hattori family, of course, but upon my call Hattori-san mentioned you were already unavailable.”

“So ya came all the way to Tokyo? From Nagoya?” Hattori’s disbelief was natural, it wasn’t as if there were a lack of exorcists in other prefectures.

Tanaka-san winced slightly. “Well, I had hoped to persuade Kudo-san – the matter is very serious, I couldn’t endanger amateurs!”

Everything was ‘serious’ to the complainant, Conan would only make the judgement upon seeing the crime scene himself.

Mouri Kogoro huffed. “Kudo? He’s still a kid! And so are  _ you _ , actually,” he said to Hattori, “Tanaka-san, it’s good that you came to me. I, Mouri Kogoro, will definitely help rid your home of all evil spirits!”

“Oh, thank you, thank you!” Tanaka-san shook hands with great fervor, promising to arrange transport for all of them and arrange for the stay at his house for as long as the procedure needed.

“Ah well,” Hattori had said as they piled into the car, “guess we can take a look at this case first before coming back to yours, eh Kudo?”

Conan only hissed at him to be quiet. “It’s Conan, stop doing that!”

And thus, they were on their way to Fullmoon Castle.

* * *

The first thing Conan noticed upon arrival was how huge the mansion was.

Hattori whistled, “I guess they don’t call it a  _ castle _ fer no reason.”

Mouri Kogoro had to agree. “How many people even live here?”

“Ah, I have a few friends over,” Tanaka-san said, “and there’s the staff, of course. Between us the place is lively enough – er, well, now there are the spirits too…” 

He trailed off nervously, wiping at his brow again. Conan and Hattori exchanged a look and finding each other on the same page, nodded.

“Ossan, I’m gonna go take a round of the grounds,” Hattori told Kogoro, “we’ll meet you in a bit, yeah?”

Tanaka-san gave a token protest and Ran cautioned them – she had been quietly apprehensive the whole journey, but hadn’t wanted to stay back either – but Hattori was already off, Conan at his heels. They scoured the grounds once and found nothing of particular interest to them, but set up some basic arrays anyway.

“Let’s see what we catch in these,” said Conan as he dusted off chalk from his fingers, giving his work a final look before stepping back in satisfaction. “Tanaka-san said he’s had some wailing spirits besiege the house, but…”

“No signs of them so far,” Hattori finished. "Especially since wailing spirits are active throughout. I think there’s something more to his story that he ain’t saying.”

The butler opened the door for them and led them to the dining hall, where everyone had seated for dinner. Tanaka-san brightened up at their arrival – clearly he held a little more faith in Hattori’s reputation than Occhan’s, considering how new his fame was in such circles.

“Hattori-san, how was it? Did you find anything?”

“Nah, we’ll see if wr get something by tonight. Who’re y’all?”

The last question was directed to the three strangers at the table. Conan gave them a curious glance; these were perhaps the friends he had mentioned.

“Ah, yes, let me introduce you – they were here when I opened the – I mean, when the mansion started getting haunted. Nakamura Seichi and Hoshino Rin – my childhood friends – they came to visit me a few days before this terrible incident began. And this is Sakamoto Minoru, he’s a journalist writing on old buildings,” here Tanaka-san gave him an apologetic glance, “he’s also a witness so I’ve asked him to stay a little longer than planned.”

The three men nodded at him, and seeing their relaxed countenance Conan guessed that they were already in the know.

“Sakamoto-san, is that right?” Hattori asked as he and Conan took their seats. “Bit of a mess you got caught up in, huh?”

“Ah haha, yes,” Sakamoto rubbed his head with a sheepish smile, “I’d heard of the rumors about the manor’s history, but looks like I got caught up in the real thing.”

“Rumors?” Conan piped up.

“Yeah,” Kogoro-occhan sighed, “Fullmoon Castle has some gruesome history behind it. Please continue from where you left off, Tanaka-san.”

“Actually,” Hattori interrupted, exchanging a glance with Conan, “we’re more interested in the current haunting.”

“I’ve already told you –”

“I gotta say you haven’t, Tanaka-han.”

Tanaka swallowed, his chopsticks freezing before his bowl. Kogoro-ochhan raised an eyebrow towards them, but Conan and Hattori had fixed their stares on their client instead of explaining. Beside Tanaka, his friend Nakamura Seichi gave a sigh.

“They need to know the full story, Kazuto,” he said, and upon receiving a resigned nod, continued, “I’ll start from the beginning.”

Nakamura Seichi was a writer who’d been looking for some quiet solitude to retreat to for writing his next novel. And when Tanaka mentioned to him that he was going to stay at the old family manion for a bit, he was invited along.

“Any reason ya chose to come now?” Hattori asked.

“Ah, I’ve recently recovered from some illness and wanted to get away from the business sector to relax,” Tanaka said, “but it wasn’t a planned outing especially. Just thought it might be good to open up this old house for a bit.”

Tanaka and Nakamura had been staying only for a week before Hoshino Rin arrived and two days after him, the journalist Sakamoto Minoru.

“My illness acted up, you see,” he explained, “and since Hoshino is a doctor – well, I thought I might be more comfortable with a friend looking after me than a hired nurse.”

“I was only supposed to stay for a day or two,” Hoshino explained, “but my arrival coincided with an unexpected note.”

“A note?”

The three friends looked at each other. Conan felt his hackles rise – this feeling, it was almost as if…

“Yes,” said Tanaka-san, “Kaitou Kid had sent a heist notice.”

Conan leaned back into his chair, a grin growing beneath his bowed head.  _ Well, well, well, this is getting interesting at last. _

* * *

Under the disguise of journalist Sakamoto Minoru, Kaito froze.  _ Wait, what?! _

When he’d sent the heist note out to Fullmoon Castle he expected a prompt arrival of the Kid Task Force and had planned to sneak into the mansion under the disguise he had donned.

_ But who knew my luck would be so bad! _ Kaito cursed silently as he heard Tanaka describe the events that took place.

“See, the jewel that KID wants – it’s cursed,” Tanaka sighed, “Normally I wouldn’t mind, that KID fellow seems to be more of a public nuisance than a threat to my property –”

Kaito choked on plain air at the casual dismissal. 

“– but you see my dilemma? How could I let an actual magical object fall into a thief’s hands?”

_ Why the hell does magic exist is what I want to know?! _

Truly, that was Kaito’s biggest grievance. Yes, okay, Akako was some kind of freakish witch-like creature with supernatural allure and Kaito was somehow immune to it. But that always seemed like a small pocket of impossibility that he had managed to stumble over.

But now?

Ever since he’d arrived at Fullmoon Castle, he’d been embroiled in one hair-rasing incident after another. Because that day when the butler had let him in, what had greeted him was a howling wind that suddenly locked down the whole mansion and some kind of flowing energy that banged into the closed doors and windows. Needless to say, Kaito had been terrified as fuck! 

Apparently, he’d turned up just as Tanaka had decided to perform some ill-fated magic. And to think it had been because of his heist note! 

_ Next time, _ Kaito vowed,  _ I'll just directly send to Nakamori-keibu! _

“The family grimoire?” Kogoro asked in surprise.

Tanaka nodded, “I opened it with Seichi and Rin – we were trying to look for some suitable protective charms to put on the jewel.” He grimaced, “Well, you understand what happened next…”

“Ya released some old malicious spirits?” Hattori sighed, “Why didn’t ya be more careful – ah forget it. It sounds like an accidental reawakening, so we gotta be cautious. Y’all got some decent repelling talismans ready to use?”

This time, it wasn’t just Kaito who was having a deer-in-headlights moment. 

“What? None of ya do?”

Kaito wanted to groan – more importantly, he wanted to get the hell out of here and as fast as possible. Unfortunately, because of some weird perimeter effect, no one but Tanaka Kazuto had been able to leave the boundaries of the plot. Else Kaito would have ran for the hills the moment he could.

It was only because of his poker face that he’d survived the continuous barrage of improbable information thrown onto him. Most surprising of which definitely had to be the arrival of  _ tantei-kun _ . Actually, the whole Mouri family turning up, really. What was this family  _ not _ involved in?

“Never mind,” Mouri Kogoro said, his daughter was already pulling out a sheaf of papers from her bag, “we’ll draw you some –”

_ Screech! _

Kaito tensed at the high pitched sound; it was like something was dragging nails on a chalkboard; loud and piercing and surrounding them from every side. Almost everyone jumped up at the same time –

“Get to higher ground,” roared Mouri, already rushing towards the stairs. “Which is your safest room?” 

A couple of days ago and Kaito would have thought they meant a panic room. But now he knew it meant  _ magically _ safest. 

“Library!”

Naturally, all of Tanaka’s spellbooks were in there after all. Safely esconced inside, Kaito finally realised that two people were missing.

“Where’s the kid?”

Surprisingly, instead of worrying about it, Mouri Ran smiled, “Oh, Hattori-kun and Conan-kun went outside to check the situation.”

Kaito startled. “The kid too?! Isn’t that dangerous?”

“Nah, he’ll be fine,” Kogoro said as he locked the windows and sat down to draw talismans, “between him being able to see the freaky spirits and that Hattori’s spirit dispelling katana, they’ll be good.”

See _what_?! _What_ type of katana?! What the absolute hell! 

Kaito slumped down in an armchair. He wanted to go home already!

* * *

When Conan and Hattori had finally taken down one spirit, they naturally ran the perimeter again to see if any of the other arrays had caught something as well.

“See anything?” Hattori asked.

Conan shook his head. “Not even any residual energy – I don’t understand, spirits being able to lockdown the whole castle and causing so much ruckus, yet –”

“Yet we managed to take them down in one go, huh?”

“Yeah, this doesn't feel like an old family spirit – hey, what’s that!”

Hattori squinted his eyes in the direction Conan was pointing, finally noticing what had caught his attention. They hurried over to the trees lining the border. A few deep gouges had been carved into the trunk.

“Seems like the work of beasts, not ghosts,” said Hattori finally.

“Yeah…”

“What, you got another opinion?”

“No, something doesn’t feel right here though.”

“That I gotta agree with. Anyway, let’s just go back and rest for now.”

Conan yawned just as Hattori spoke those words. It had been a tiring day after all, they deserved a rest. By the time the two of them made their way to the library, talismans and been stuck on every available surface and a collective decision to go to bed had been made.

“They’ve not been able to enter the house yet!” Tanaka made a convincing argument, “I’ll bring out the grimoire for you tomorrow morning!”

Conan agreed with that course of action, so he and Hattori quickly claimed a room for themselves to rest.

“I’ve sent a text to Kazuha,” Hattori said as he got under the covers, “she knows spiritual beasts better than I do. Let’s see if she knows what could have caused that horrific gouge in the tree.”

“Good idea!”

* * *

Staying three nights in this house were enough for Kaito – it was three nights too many if you asked him! Okay, so he’d received a few protective talismans this time, but he didn’t want it! What he wanted was to be as far away from this whole mess as possible. 

He’d also been teetering on the edge of a decision for a while now, but seeing how the  _ detectives _ seemed far less phased than him when there was a literal mad ghost roaming about – well, he might as well do it.

Kaito pulled out his phone and called Akako.

“Hohoho,” Akako laughed daintily, dangerously, “you seem to have gotten yourself in quite a pickle!”

“Cut to the chase, can you help or not?”

“Hmm, what do I get from this?”

Kaito grit his teeth, buckling down to bargain – when she laughed again.

“This can be a free one,” Akako said magnanimously.

Kaito frowned, suspicious at the generosity –

“Remind those spirit detectives about the old curse of the Fullmoon Castle. They’ll have the answer themselves.”

– and Kaito had already been hung up on. No wonder she called it a “free one”! She barely said anything at all!

_ What even am I going to tell Tantei-kun and Tantei-han though? I have never heard of the curse at all! _

* * *

It was past midnight when Hattori's phone went off, pinging like crazy –

_ Heiji!!  _

_ Ahou, are you already asleep??! _

_ Come back here  _

_ what the hell are you even doing chasing after werewolf spirits?? _

_ HEIJI _

_ Oy don't underestimate them!!! Even if conan-kun can see them they're nor easy to dispel  _

_ Hello wake up donr waste time!! _

_ Have yoe forgotten what day it is today!!! _

_ Oh god Kazuha shut it _

_ What  _

_ FULLMOON _

Heiji bolted up from bed, bleary eyes wide awake now – the words connecting all too well. Werewolf spirits and full moon, could there be anymore doubt as to what had made those gouges in those trees?

A light tap on Kudo's shoulder woke him up and he shoved the phone under his eyes.

"Wait," Kudo said after reading, "all that makes sense – but what about the spirit we caught today in that array?"

Heiji had also grasped upon this inconsistency. "Yeah, that bit is troubling me –"

Knock knock!

Heiji and Kudo turned towards the door, alert. Who was awake so late at night? 

It turned out to be the journalist. He had a sheaf of papers in his hand and looked harried, yet also grateful to see them awake.

"Fullmoon Castle's old curse," he gasped out, "they had one weak point – I did my research before coming here – you should know what it is! The powers of this place decreased on the day of the full moon; so to strengthen their defences –"

"They used to summon werewolf spirits!" Kudo darted out of the room, Heiji hot on his heels only a moment later after grabbing his katana.

"Hey, where are you going – what did you figure out, oh wait, don't leave me behind!"

The journalist's words were slightly confusing as he ran after them. Hadn't he also reached the conclusion they had? 

The werewolf spirits were protective, so why would they damage the property? Obviously, it was to counter the other malicious spirits that were attacking. But if the grimoire had summoned the werewolf spirits, then who had summoned the malicious one? 

Not Tanaka. That was the first thought in his mind; so that left his two companions Nakamura and Hoshino. If one of them had summoned the spirits, then the best time would be to attack now – now when everyone had thought that the attack had subsided, and before Heiji could fully exorcise the manor. 

"Dammit, who is the target though?" 

Kudo shook his head as they searched through the rooms. "I don't –" 

He froze, his eyes catching something Heiji couldn't see but definitely feel. Even Sakamoto, the journalist, shivered.

"How many?" He readied his katana.

"Three!" 

Heiji exchanged a glance with him. Three was a bit too much, especially when Kudo's ability was slightly suppressed due to his weak body constitution. But he was sure they could manage it.

"Oy, Sakamoto-han, make sure to keep your distance!" 

And then, they gave chase.

* * *

Kaito didn't know what was going on anymore, but he happily complied with that order. Not too close and not too far, that was a good distance to maintain. 

After his call with Akako, he'd decided to search up the so called "old curse" of Fullmoon Castle. It wasn't like he could give tantei-kun a cryptic message like that and not come under suspicion himself! Carefully combing through some old websites, Kaito had jotted down some crucial points. As for whether they actually contained a clue? Who knew! 

Both tantei-kun and tantei-han had reacted instantly though, so he supposed it  _ was _ a crucial clue. 

Kaito ran after them all the way to the ballroom on the ground floor. Conan came to a stop in front of the closed door.

"They passed through!"

Was he still talking about ghosts? Kaito had seen nothing, and from what it seemed like, neither had Hattori. 

_ Fuck, you were the last person I would have expected to be mixed up in this supernatural mess, tantei-kun! _ Kaito only had a brief moment of wondering what they would do, when Hattori straight up kicked at the door.

Bang! 

… and just like that, they were through? Kaito had one small instance of absolute incredulity, before he had to yelp and dive for cover. There was clearly some kind of sound-proofing inside the room, because it was a legitimate battle going on inside. 

Ghosts swirled through the air, randomly swooping down with their absurdly solid hands to clutch at the person crouching in a corner. The translucent shield suspended over him was his only defense as he cried out to his attacker, begging him to stop. Of course, Kaito couldn't see the ghosts, but there was an unmistakable wailing and screeching and cold energy that blasted out in every direction.

"Wait," Kaito mumbled, squinting at the attacker, "isn't that Nakamura? And the other guy… Hoshino!"

Old friends? More like old enemies! Kaito hadn't noticed such a tension between them in the two days he'd been here, but to think they'd resorted to summoning malicious ghosts! What enmity was this? A fight to the death?

The two of them hadn't even turned to see the arrival of the two detectives. It was in that moment that Hattori struck - clearly this was a fighting style they were used to. Kaito saw him first target Nakamura, who jumped back to avoid the blade, but it was enough to interrupt his control over the ghosts. 

In the next moment Conan had raised his hands in a similar fashion, palms splayed out. For a moment nothing happened, then the silence descended upon them. And even Kaito could tell that he had stopped the ghosts with how still the air became.

* * *

"Hurry!"

Conan didn't have to say it twice. Hattori concentrated his attack towards where he'd positioned the spirits, the first one dispelled faster than the second. His control over them was wavering because Nakamura once again tried to regain control. 

From the corner of his eye he saw Sakamoto rush in, taking only a few seconds to grab at Hoshino – who appeared quite stunned at the help he had received in such a timely fashion – and drag him outside the door. Nakamura roared in fury, giving up on the ghosts and simply lunging towards his fleeing target, just to stumble right into Occhan. 

Mouri Kogoro had clearly run down as soon as the loud wailing had begun. And upon getting run into, he didn't stop to ask - he simply judo flipped him over his shoulder. 

Conan brightened upon seeing Ran right behind him. "Ran-nee-chan, that man is from a demonic clan too! He can see ghosts!"

Ran didn't need any more of an explanation, pulling out a talisman from her sleeping gown and slapping it over Nakamura's eyes.

The last to arrive was Tanaka, with his butler right behind him. Frazzled, he took a look over the scene but came to no conclusion.

_ Swoosh. _

With one last hit, Hattori had finally eliminated the third spirit. He rested the blunt edge of his katana on his shoulder and looked at the two men involved. 

"Ya know, I still don't get this. And since we are all awake anyway, why don't y'all give us an explanation?"

* * *

With the last ghost gone, the oppressive feeling that Kaito had felt since that first night was finally gone. He knew then that if he tried to escape now he would be able to, no perimeter ward would stop him. 

Only… seeing the informal hearing taking place and the overly alert stances, he knew leaving now would draw too much attention. So he settled down in a convenient spot to listen. 

"You know the haunted house you once dared me to enter?" Nakamura began with a slightly manic laugh, "Did you think just because I could see ghosts, it would be fine?"

Hoshino blinked in surprise, "That's over twenty years ago!"

"Exactly! Twenty years ago!  _ Twenty years _ – I was a kid – I had no control over spirits back then," Nakamura leaned in, his voice a menacing whisper, _"I_ _ nearly died!" _

"Wait," Mouri dragged a hand down his face, "you mean to tell me this was all over some stupid dare from your childhood? Why didn't you just refuse?"

"How could I! It was a matter of pride – out of everyone, I was the only person who could see ghosts. Every time someone heard of a haunted house, they would come to me – Seichi, go check it out! Seichi, tell us, are there actually ghosts in there?" Nakamura shook his head, "Most of those houses weren't haunted, but I still went in and checked them out. Then, Hoshino…"

"But it was an accident, wasn't it?" Ran said, "Even if there were ghosts in there, none of you knew that!"

"HA! An accident? Was it so – ask him! ASK HIM!"

Beside him, Hoshino Rin had already paled. "I never… I never thought – Seichi, I didn't mean to –"

Tanaka only stared blankly at his two friends, overwhelmed. In the end, whether it was some mischief or out of malicious intent, with over twenty years of misunderstanding between them, the festering resentment over a life nearly lost had only grown. 

Kaito quietly walked out of the gates when everyone's attention was diverted. Overhead, the full moon was shining in splendour but Kaito had no jewel to hold up to it today.

"Ah," he sighed, "guess this heist will have to be rescheduled."

Hopefully there would be no surprise appearances of unwelcome ghosts next time. Once was more than enough!

* * *

_ Omake _

"Oi where did that journalist go?" Hattori asked suddenly.

"Eh, he ran at the earliest possible chance of course," Conan said, a smirk on his lips, "his plans for stealing the jewel didn't exactly go as intended, after all."

Hattori's eyes widened, "That was KID?"

"I'd really like to know what kind of ordinary person would remain so unphased in this situation – did you see him run into the ballroom and get out in five seconds flat? It had to be KID!"

"Heh, your demonic powers can help you see phantom thieves now? Or is it that… what does that tiny nee-chan call it? Kid-sense? Really diversifying there, huh Kudo?"

Conan kicked at Hattori's shin, his eyebrow twitching. "Shut up!"

Hattori only laughed.

**Author's Note:**

> Basically, Shinichi is partly demon who can see ghosts? Akako is a witch of course. Kaito as the confused bystander. Heiji as an exorcist, Kazuha a shrine maiden? 
> 
> Hope you enjoyed it!!!   
> Please leave me a comment, it would make my day ^_^


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